These days, we're working longer hours and sleeping less, with our personal relationships squeezed into the few remaining minutes. It's no wonder we're always chasing the next get-fit-quick scheme—the "Shake Weight," 5-minute abs, or a diet that promises we can eat everything we love and still lose weight. Usually, these fads are a waste of time. But scientists in California may be making breakthroughs with a drug called 516.

It's "exercise in a pill," says Ronald Evans, who's leading research on it at the Salk Institute for Biological Studies in California. Before you get too excited about a pill with the potential to replace the grueling chore of exercising to get you fit and thin, here's everything you should know about 516.

What is 516?

Scientists have been working with a chemical compound called 516 for about a decade now. They think they can use it to get your body to break down fat instead of carbohydrates by altering the signals that your genes send to your muscles. Elite athletes burn fat when they exercise, not carbs, so 516 could mimic the effects of high performance training while cutting down on the sweat.

How does it work?

We all define exercise as physical activity that burns calories and builds muscle. But when you really think about it, exercise just triggers a chemical process at the molecular level that helps us lose weight and get strong. So these pills are attempting to trigger that process without exercise. As Evans told The Washington Post, he's trying to "develop a drug that can help us game the system that is naturally activated during exercise."

Why?

Because exercise is really, really good for you, and there are some people who are physically incapable of doing it. Think of people who are injured, people with genetic disorders that prevent them from building muscle, the elderly, and the obese. With 516, they could reap the benefits of the exercise their bodies won't let them do.

This seems too good to be true.

Yeah, scientists aren't making 516 just so you can cancel that gym membership. And it's still in trial stages. Plus, in an earlier study done with a stronger dosage of 516 than what Evans and others are studying now, mice were more likely to develop cancer, the New Yorker reports. You're taking a compound that alters genetic and molecular signals in your body, after all. There are risks involved.

Is it the only exercise pill out there?

No, scientists are working on other drugs to hack exercise, including compound 14. Compound 14 gets your body to break down sugar “by fooling cells into thinking they have run out of energy,” says chemical biology professor Ali Tavassoli, who discovered it. That could be hugely beneficial for people with diabetes, obesity, and more. But unlike 516, compound 14 is "quite a way" from human testing.

Who can take 516 now?

Experimental versions of 516 have been on the market for awhile and were especially popular among muscle builders and athletes, leading to them being banned by the World Anti-Doping Agency. As for science-approved versions of 516, there are still trials to be run. Right now, the FDA won't approve 516 because it doesn't consider "inability to exercise" a disease in need of a drug. So for now, Evans is targeting young people with Duchenne muscular dystrophy—people with a real need. If 516 can benefit them, then the FDA would be much more likely to approve it for wider use.

In the meantime...

Don't hold your breath. 516 is still "multiple trials and several years" away from hitting your pharmacy's shelves, according to the New Yorker. Until then, the only way to get all those amazing benefits from exercise is to actually exercise.

In the meantime, check out the video above to learn about some common workout myths.